Plastics



Patented Nov. 20, 1 934 UNITED STATES PLASTICS Texas No Drawing. Application October Serial No. 636,337

12 Claims.

; novel sulphur products.

The present invention is based on our discovery that arsenic phosphorus, and thallium and compounds containing those elements are effective stabilizers of amorphous or non-crystalline sulphur and effectively retard or inhibit crystallization of plastic sulphur.

When elemental sulphur is heated to a temperature above about 200 C. and then rapidly chilled to a temperature below its melting-point, an amorphous, plastic sulphur product is formed. The product thus formed, however, is unstable and loses its plasticity and crystallizes within about twenty-four hours.

We have discovered that when arsenic, phosphorus or thallium or a substance containing one of those elements is dispersed in sulphur heated to the temperature indicated and the resulting product is cooled to a temperature below its melting-point, a relatively stable plastic sulphur product is formed.

According to a preferred process of our invention, elemental sulphur is heated with a suitable stabilizing agent to a temperature above 200 C. until the stabilizing agent has been dispersed throughout the molten sulphur to form a homogeneous fluid. The molten material may be stirred or otherwise agitated during the heating operation to aid dispersion or solution. The resulting fluid is then cooled rapidly to a temperature below its solidifying point, preferably by passing it in finely divided form into a cooling liquid. Any suitable method may be employed in subdividing the fluid mass to obtain small particles or threads which will facilitate cooling.

; Thus, for example, the fluid may be poured in a Our researches indicate that, among others, the following factors are of importance" in the production or stabilization of plastic sulphur:

(1) Type of stabilizing agent;

(2) Amount of stabilizing agent;

(3) Quenching temperature;

(4) Quenching fluid;

(5) Heating temperature; and

(6) 'Time of heating. The sulphur should ,beheated with a suitable amount and type of stabilizing agent until a sub.- stantially homogeneous fluid has been formed.

The results of our tests indicate that water at temperatures from about 0 C. to about-.160 C. is the most suitable quenching fluid. Products formed by quenching at a temperature of 195 C. and above +60 C. and by quenching in sulphuricacid and nitric acidat 0 C. lose their plasticity more rapidly than products quenched at intermediate temperatures and in water at temperatures of about 0 C. to 60 C. Quenching temperatures ranging from 'l0 C. to +60 C. appear to be most suitable for the production of plastic sulphur.

The time of heating the sulphur with the stabilizing agent is determined by the time required for dispersing or dissolving the stabilizing agent. In general, when the temperature is sufliciently high to initiate dispersion or solution, a tenminute heating period is sufiicient.

Some of the data obtained in testing various stabilizing agents at different heating temperatures indicate that similar quantities of certain agents are equally effective at all heating temperatures while other data indicate that with respect to other agents larger quantities must be employed at lower temperatures. Thus, for

example, similar quantities of arsenic disulphide (AS252), arsenic trisulphide (AS2S3), and phosphorus trisulphide (Pass) are equally efiective at temperatures of 200 C., 300"v C. and 440 C., while the quantity of phosphorus pentasulphide (P235) is inversely proportional to the heating temperature, about 23% being required to produce at 200 C. and 300 C. results equal to the results produced by about l0% to 14% at 440 C.

The following tables show some of the amounts of arsenic and phosphorus and compounds of arsenic and phosphoruswhich are effective in stabilizing plastic sulphur when incorporated in elemental sulphur at various temperatures (the percentages given define the proportions by weight of the stabilizing agents in the plastic sulphur products) Table I Elemental Phosphorus Phosphorus gz phosphorus trisulphide pentasulphide Percent Percent Percent 200 C l0 .23. 300 C 10 23. 07 440 C 2 91 to 4.76 2.31 to 8.25 8.25 to ;8

Table II Arsenic Arsenic Arsenic lgg i ffs disulphide trisulphide trioxide (Asst) (Asst) (AS203) Percent Perce'rt Percent l l0 l0 10 to 17. 35 10 to 16. 66 9 9 17011 5 Th allium and its compounds appear to be effecti've stabilizers of plastic sulphur, but the results obtained thus far indicate that excessive amounts, varying, from 10% to 40%, are required.

For the stabilization of plastic sulphur with.

elemental phosphorus, it is advisable to employ red phosphorus, as yellow phosphorus reacts with sulphur with explosive violence.

All proportions of phosphorus, arsenic, and thallium-bearing substances tested were effective in retarding or inhibiting crystallization of sulphur. In every instance an amorphous prodnot was formed, and in practically every instance the product was plastic initially and for atleast one week after its production. The amounts oi phosphorus?arsenic, and compounds of phosphorus and arsenic set forth in Tables I and II have been employed to form products which remain; plastic at least for several months; and some of which, at least, appear to have been rendered permanently plastic.

All of the plastic products become slightly harder with age at normal room temperatures. Some or the initially plastic products harden gradually for several weeks and ultimately approach a stable plastic state. Other products hardengradually until they reach a stable vitreous state. The vitrifying process is slow at ordinary room temperatures, but it can be accelerated by subjecting the plastic product to-the effects of higher temperatures, particularly temperatures above C. Thus, for example,,freshly prepared plastic sulphur can be completely vitrified v by maintaining it at a temperature of 'C. for sixteen-hours. The resulting vitreous product shows no crystalline structure; it is a dense, even mass possessing a fracture. resembling that of glass, and it appears tobe stable.

Plastic and vitreous sulphur products soften or melt at approximately 120 C. At temperatures of from 120 C. to the boiling-point, these forms of sulphur are exceedingly viscous. Both forms of sulphur are soluble in the Aroclors (chlorinated diphenyls).

Plastic sulphur can be heated to temperatures above its melting-point and cooled gradually to room temperature without destroying its plasticity,

Wec1aim:- I 1;"The method of producing plastic sulphur which comprises heating a mixture of elemental sulphur and an arsenic sulphide to a temperature above 200 C., and rapidly cooling the resulting fluid to a temperature below the melting point of sulphur, the amount of arsenic sulphide employed being equal to about 10% of the weight of the mixture.

2. The method of producing plastic sulphur which comprises heating a mixture of elemental sulphur and an arsenic sulphide to a temperature above 300 C., and rapidly cooling the resulting fluid to a temperature below the melting point of sulphur, the amount of arsenic sulphide employed being equal to about 10% of the weight of the mixture.

:3. The methodof producing plastic sulphur which comprises heating a mixture of elemental sulphur and elemental arsenic to a temperature above 300 C., and rapidly cooling the resulting fluid to a temperature below the melting point of sulphur, the amount of elemental arsenic employed b'eing'equal to about 10% of the weight of about 440C, and rapidly. cooling the resulting fluid to av temperature below the melting point.

of sulphur, the amount of elementalarsenic employed being equal to about 13% of the weight of the mixture. I

=5." The method of producing plastic sulphur which comprises heating a mixture of elemental sulphur and an arsenic sulphide to a temperature of about 200C. to 440 C., and rapidly cool-.

ing the resulting fluid to a temperature below the melting point of sulphur, the amount of arsenic sulphide employed being equal to about 10% to 17.35% of the weight of the mixture.

6. The method of producing plastic sulphur which comprises heating a mixture of elemental sulphur and an arsenic oxide to a temperature of about 440 C., and rapidly cooling the resulting fluid to a temperature below the melting point of sulphur, the amount of arsenic oxide employed being equal to about 9.9% to 11.5% ofthe weight of the mixture.

'7. The method of producing plastic sulphur which comprises heating a mixture of elemental sulphur and an arsenic sulphide to a temperature above 200 C., and rapidly cooling the resulting fluid to atemperature of about 0 C. to 60 C., the amount of arsenic sulphide employed being equal to about 10% of the weight of the mixture.

8. The method of producing plastic sulphur which comprises heating a mixture of elemental sulphur and an arsenic sulphide to a temperature above 300 C.,.and rapidly cooling the resulting above 300 C.,andrapidly cooling the resulting 314G,

fluid to a temperature of about 0 C. to 60 C., the amount of elemental arsenic employed being equal to about 10% of the weight of the mixture.

10. The method of producing plastic sulphur which comprises heating a mixture of elemental 5 sulphur and elemental arsenic to a temperature of'about 440 C., and rapidly cooling the resulting fluid to a temperature of about 0 C. to 60 C., the amount of elemental arsenic employed being equal to about 13% of the weight of the mixture.

which comprises heating a mixture of elemental sulphur and an arsenic oxide to a temperature of about 440 C., and rapidly cooling the resulting fluid to a temperature of about 0 C. to 60 C., the amount of arsenic oxide employed being equal to about 9.9% to 11.5% of the weight of the mixture.

WILLIAM A. I-IAMOR. WERNER W. DUECKER. 

